Tube for Heat Exchanger, Heat Exchanger, and Method for Manufacturing Tube for Heat Exchanger

ABSTRACT

Provided is a tube for a heat exchanger in which drainage performance of the tube and the fin is improved while preventing the brazing failure. That is, provided is a tube ( 110 ) for a heat exchanger, the tube through which a refrigerant flows being formed into a flat plate shape, the tube including stepped portions ( 117  and  118 ) at both end portions ( 110   a  and  110   b ) in a refrigerant flowing direction, respectively, in which the tube has a widthwise length in a region on an end portion ( 110   a  or  110   b ) side with respect to a position of each of the stepped portions ( 117  and  118 ), the widthwise length being smaller than a widthwise length in a region between both the stepped portions ( 117  and  118 ), and in which the tube further includes a drainage portion ( 119 ) at a predetermined position between both the stepped portions ( 117  and  118 ) along the refrigerant flowing direction.

TECHNICAL FIELD

The present invention relates to a heat exchanger, and more particularly, to a tube structure in a heat exchanger and a method of manufacturing a tube for a heat exchanger.

BACKGROUND ART

Conventionally, heat exchangers have been utilized in, for example, an air conditioning apparatus. The air conditioning apparatus includes, for example, an indoor heat exchanger and an outdoor heat exchanger. It is known that, in the indoor heat exchanger in the case of cooling operation and in the outdoor heat exchanger in the case of heating operation, condensed water is easily generated through dew condensation. The condensed water is liable to accumulate between a tube and a fin of the heat exchanger, which may inhibit an air flow to cause not only reduction in heat exchange efficiency, but also frost formation in the outdoor heat exchanger during heating operation.

To address this problem, as described in, for example, Patent Literature 1, there has been proposed a heat exchanger in which, for drainage of condensed water accumulated in the heat exchanger, a corrugated fin including an inclined portion and a curved portion is arranged between heat exchange tube portions (flat tubes) arranged in a vertical direction, and an elongated depression for drainage extending in a longitudinal direction is formed in a flat surface portion of a heat exchange tube portion on the corrugated fin side.

With such a heat exchanger, it is conceived that, indeed, the condensed water generated through dew condensation on the surfaces of the flat heat-transfer tube and the corrugated fin is guided downward through the elongated depression for drainage formed in the flat surface portion of the heat exchange tube portion.

CITATION LIST Patent Literature

-   [PTL 1] Japanese Patent Application Laid-Open No. 7-190661 (claim 1,     paragraph [0016], FIG. 4)

SUMMARY OF INVENTION Technical Problem

In this case, the elongated depression provided in the flat surface portion of the heat exchange tube portion is formed only in a range excluding end portions of the heat exchange tube portion so that, when the heat exchange tube portion is inserted into an insertion hole of a header tank and brazed, airtightness between the heat exchange tube portion and the header tank is not inhibited. In this case, when the end potion of the heat exchange tube portion, at which the elongated depression is not formed, is accurately inserted into the insertion hole of the header tank, it is conceived that the heat exchange tube portion is brazed without the airtightness thereof being inhibited as described above.

However, when the end portion of the heat exchange tube portion is inserted into the insertion hole of the header tank deeper than expected, the insertion hole and the elongated depression overlap with each other, which may cause brazing failure such as inhibition of airtightness. Further, when the end portion of the heat exchange tube portion is inserted shallower than expected so as to prevent overlapping of the insertion hole with the elongated depression, such brazing failure that a brazing material blocks the flow path of the heat exchange tube portion may occur.

The present invention has been made as a challenge to solve such a problem described above, and has an object to provide a tube for a heat exchanger in which drainage performance of the tube and the fin is improved while preventing the brazing failure, and to provide a heat exchanger and a method of manufacturing a tube for a heat exchanger.

Solution to Problem

In order to meet the challenge as described above, a tube for a heat exchanger according to the present invention and a tube for a heat exchanger to be used in a heat exchanger according to the present invention are each a tube for a heat exchanger, the tube through which a refrigerant flows being formed into a flat plate shape, the tube including stepped portions at both end portions in a refrigerant flowing direction, respectively, in which the tube has a widthwise length in a region on an end portion side with respect to a position of each of the stepped portions, the widthwise length being smaller than a widthwise length in a region between both the stepped portions, and in which the tube further includes a drainage portion at a predetermined position between both the stepped portions along the refrigerant flowing direction. Further, the widthwise length of the region on the end portion side with respect to the position of the each of the stepped portions is formed to become smaller toward the end portion. Further, according to the present invention, there is provided a method of manufacturing a tube for a heat exchanger, the method including press-forming a tube for a heat exchanger, which has a drainage portion formed therein at at least one widthwise side end portion along a refrigerant flowing direction, to thereby flatten parts of the drainage portion at both end portions in the refrigerant flowing direction so that a width of each part obtained by the flattening is smaller than a width between both side end portions.

Advantageous Effects of Invention

According to the present invention, it is possible to provide the tube for a heat exchanger in which drainage performance of the tube and the fin is improved while preventing the brazing failure, and to provide the heat exchanger and the method of manufacturing a tube for a heat exchanger.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic front view of a heat exchanger according to an embodiment of the present invention.

FIG. 2A is a perspective view of a tube of the heat exchanger according to the embodiment of the present invention.

FIG. 2B is a longitudinal end view of the tube.

FIG. 2C is a sectional view taken along the line A-A of FIG. 2A.

FIG. 3 is a perspective view of an unprocessed tube of the heat exchanger according to the embodiment of the present invention.

FIG. 4A is a schematic view illustrating a step of a method of manufacturing a tube.

FIG. 4B is a schematic view illustrating a step of the method of manufacturing a tube.

FIG. 4C is a schematic view illustrating a step of the method of manufacturing a tube.

FIG. 4D is a schematic view illustrating a step of the method of manufacturing a tube.

FIG. 5A is a perspective view of a tube of a heat exchanger according to another embodiment of the present invention.

FIG. 5B is a sectional view taken along the line B-B of FIG. 5A.

FIG. 6 is a perspective view of an unprocessed tube of the heat exchanger according to the another embodiment of the present invention.

FIG. 7 is a configuration view illustrating an example of an air conditioning apparatus including the heat exchangers.

DESCRIPTION OF EMBODIMENTS

In the following, embodiments of the present invention are specifically described with reference to the drawings. For the sake of convenience, parts having the same action and effect are denoted by the same reference symbols, and description thereof is omitted herein.

First Embodiment

As illustrated in FIG. 1, a heat exchanger 100 includes a plurality of tubes 110 arranged in parallel to each other, through which a refrigerant flows, and fins 120 each joined by brazing between adjacent tubes 110. In the illustrated example, the plurality of tubes 110 are communicated to hollow header tanks 130 and 135 at both ends of the plurality of tubes 110 in their longitudinal direction (refrigerant flowing direction). The header tank 130 provided on the upper side includes a refrigerant entrance portion 130 a provided on one end side, a refrigerant exit portion 130 b provided on the other end side, and a partition plate 131 provided at a center thereof, for partitioning inside of the header tank 130. With this, the refrigerant flowing in from the entrance portion 130 a of the header tank 130 flows through the tubes 110 (two tubes on the left side in FIG. 1) communicated on the entrance portion 130 a side with respect to the partition plate 131, and flows into the header tank 135 provided on the lower side. Then, the refrigerant exits from the header tank 135 to flow through the tubes 110 (two tubes on the right side in FIG. 1) communicated on the exit portion 130 b side with respect to the partition plate, and flows out from the exit portion 130 b via the header tank 130. Note that, FIG. 1 schematically illustrates the heat exchanger 100, and is simplified for the sake of easy understanding of the description.

The fin 120 is a so-called corrugated fin and is made of a metal having high heat conductivity, such as aluminum. The fin 120 includes a flat portion 121 having a flat plate shape and a bent portion 122 bent with a predetermined curvature radius, which are formed alternately in the longitudinal direction. The bent portion 122 is a part to be joined to a flat surface 115 of the tube 110, and includes a first bent portion 122 a to be joined to the flat surface 115 of one of the opposing tubes 110, and a second bent portion 122 b to be joined to the flat surface 115 of the other of the opposing tubes 110 (see FIG. 1). In the illustrated example, the flat portion 121 is smoothly and continuously provided to the bent portion 122 (122 a and 122 b) formed into a semi-circular arc shape in cross section. With this, adjacent flat portions 121 are provided in parallel to each other. Further, when the fin 120 is joined to the tube 110, the flat portion 121 becomes perpendicular to the longitudinal direction of the tube 110.

As illustrated in FIG. 2A, the tube 110 is formed into a flat hollow plate shape and is made of a metal having high heat conductivity, such as aluminum. Further, in an inside space, a plurality of partition portions 113 are provided so that a plurality of refrigerant flow paths 111 extending in a longitudinal direction are arranged in parallel in a width direction (lateral direction). As illustrated in FIG. 1, the plurality of tubes 110 are equally arranged in parallel at predetermined intervals so that the flat surfaces 115 thereof are opposed to each other, and the fin 120 is joined to the opposing flat surfaces 115 of the adjacent tubes 110. The tube 110 has two longitudinal end portions 110 a and 110 b, which are inserted into insertion holes provided in the header tanks 130 and 135, respectively, and are brazed. Note that, the insertion ports are provided in conformity with the shape of both the end portions 110 a and 110 b of the tube 110.

In each of both widthwise (lateral) end portions of the tube 110, a stepped portion 117 and a stepped portion 118 are formed on one end side (end portion 110 a side) and the other end side (end portion 110 b side) in the refrigerant flowing direction (longitudinal direction), respectively. Further, the widthwise length of a region further on the one end side (end portion 110 a side) with respect to the position of the stepped portion 117 is smaller than the widthwise length of a region between the stepped portion 117 and the stepped portion 118 by the length of the stepped portion 117 (see FIGS. 2A and 2B). Further, similarly, the widthwise length of a region further on the other end side (end portion 110 b side) with respect to the position of the stepped portion 118 is smaller than the widthwise length of the region between the stepped portion 117 and the stepped portion 118 by the length of the stepped portion 118.

An outer shape of the region further on each end portion 110 a or 110 b side with respect to the position of the stepped portion 117 or 118 is a simple shape that is formed of linear portions 114 formed by the flat surfaces 115 and 115, and semi-circular arc portions 116 and 116 formed at both ends of the linear portions 114. Note that, the widthwise length of the region further on each end portion side with respect to the position of the stepped portion 117 or 118 may become smaller toward the end portion from the position of each stepped portion 117 or 118 to form a tapered shape in plan view.

Between the stepped portion 117 and the stepped portion 118, a drainage portion 119 is provided at a predetermined position in the refrigerant flowing direction. In the illustrated example, the stepped portions 117 and 118 are provided at predetermined positions between both the end portions 110 a and 110 b in the refrigerant flowing direction, and the groove-shaped drainage portion 119 is formed between the stepped portions 117 and 118. Further, as illustrated in FIG. 2C, the tube 110 has two widthwise ends that are formed into semi-circular arc portions 112 having a semi-circular arc shape. The above-mentioned drainage portion 119 is arranged at a boundary between the semi-circular arc portion 112 and the flat surface 115.

The drainage portion 119 is formed in the tube 110 as described above, and hence, even when the fin 120 is joined to the tube 110, the drainage portion 119 is not blocked by the fin 120. With this, condensed water accumulated inside the fin 120 or between the fin 120 and the tube 110 is drained downward through the drainage portion 119.

Further, the region further on each end portion side with respect to the position of the stepped portion 117 or 118 is not provided with the drainage portion and has a simple shape. Therefore, brazing failure hardly occurs when the tube 110 is inserted into the header tanks 130 and 135 and brazed.

Further, the width of the insertion hole for the tube 110, which is provided in each of the header tanks 130 and 135, is provided in conformity with the width of the region of the tube 110 further on each end portion side with respect to the position of the stepped portion 117 or 118, and hence, when the tube 110 is inserted to reach a predetermined position (position of the stepped portion 117 or 118), the stepped portion abuts against the insertion hole, and the tube 110 cannot be inserted any more. With this, the drainage portion 119 and the insertion port are prevented from overlapping with each other, and hence the brazing failure hardly occurs.

Further, when the tube 110 is processed so that its width becomes narrower toward each end portion from the position of the stepped portion 117 or 118, the end portion of the tube 110 can be easily inserted into the insertion port of each of the header tanks 130 and 135.

A method of manufacturing the tube 110 is described with reference to FIGS. 3 and 4. An unprocessed tube 140 illustrated in FIG. 3 is formed by, for example, extrusion molding to have an outer shape formed of linear portions 144 formed by flat surfaces 145 and 145, and semi-circular arc portions 142 and 142 formed at both ends of the linear portions 144. Further, a drainage portion 149 is formed across an entire longitudinal region at a boundary between the semi-circular arc portion 142 and the flat surface 145. Note that, a distance (widthwise length) between one semi-circular arc portion 142 to the other semi-circular arc portion 142 is the widthwise length of the tube 110 in the region between the stepped portion 117 and the stepped portion 118.

Such an unprocessed tube 140 is fixed to a press forming machine, and predetermined regions on sides of both lengthwise end portions 140 a and 140 b are pressed in the width direction by a pair of dies 150 and 150 each having a depression portion corresponding to the outer shape of the region further on each end portion 110 a or 110 b side with respect to the position of the stepped portion 117 or 118 (FIGS. 4A and 4B). With this, in the predetermined regions of the unprocessed tube 140 on the sides of both the end portions 140 a and 140 b, the drainage portion 149 is squashed to be flattened. Thus, a predetermined region of the semi-circular arc portion 142 becomes the semi-circular arc portion 116 (FIG. 4C). The unprocessed tube thus formed is removed from the dies to become the tube 110 (FIG. 4D).

Second Embodiment

FIG. 5 illustrates a tube 210 of a heat exchanger 200 according to a second embodiment of the present invention. Note that, the tube 210 of the second embodiment illustrated in FIG. 5 has a configuration in which the tube 210 having a structure different from that of the tube 110 of the heat exchanger 100 of the first embodiment is provided. Therefore, description other than that of the tube 210 is omitted herein.

The tube 210 is formed into a flat hollow plate shape and is made of a metal having high heat conductivity, such as aluminum. Further, in an inside space, a plurality of partition portions 213 are provided so that a plurality of refrigerant flow paths 211 extending in a longitudinal direction are arranged in parallel in a lateral direction (width direction).

In each of both widthwise (lateral) end portions of the tube 210, a stepped portion 217 and a stepped portion 218 are formed on one end side (end portion 210 a side) and the other end side (end portion 210 b side) in the refrigerant flowing direction (longitudinal direction), respectively. Further, the widthwise length of a region further on the one end side (end portion 210 a side) with respect to the position of the stepped portion 217 is formed smaller than the widthwise length of a region between the stepped portion 217 and the stepped portion 218. Further, similarly, the widthwise length of a region further on the other end side (end portion 210 b side) with respect to the position of the stepped portion 218 is formed smaller than the widthwise length of the region between the stepped portion 217 and the stepped portion 218.

An outer shape of the region further on each end portion 210 a or 210 b side with respect to the position of the stepped portion 217 or 218 is a simple shape that is formed of linear portions 214 formed by the flat surfaces 215 and 215, and semi-circular arc portions 216 formed at both ends of the linear portions 214. Further, the widthwise length of the region further on each end portion 210 a or 210 b side with respect to the position of the stepped portion 217 or 218 becomes smaller toward the end portion 210 a or 210 b from the position of each stepped portion 217 or 218 (unrecognizable in the figures), and hence the end portion 210 a or 210 b of the tube 210 can easily be inserted into the insertion port of each of the header tanks 130 and 135.

Between the stepped portion 217 and the stepped portion 218, a drainage portion 219 is provided at a predetermined position in the refrigerant flowing direction. As illustrated in FIGS. 5A and 5B, the stepped portions 217 and 218 are provided at predetermined positions between both the end portions in the refrigerant flowing direction, and the drainage portion 219 having a cutout shape continuously provided in the refrigerant flowing direction is formed between the stepped portions 217 and 218. Note that, a region on the outer side in the width direction with respect to the drainage portion 219 is formed to have a semi-circular arc shape (semi-circular arc portion 212), and has a curvature radius smaller than the curvature radius of the semi-circular arc portion 216 on the end portion side.

The drainage portion 219 is formed in the tube 210 as described above, and hence, even when the fin 220 is joined to the tube 210, the drainage portion 219 is not blocked by the fin 120. With this, condensed water accumulated inside the fin 120 or between the fin 120 and the tube 210 is drained downward through the drainage portion 219.

Further, the region further on each end portion 210 a or 210 b side with respect to the position of the stepped portion 217 or 218 is not provided with the drainage portion 219 and has a simple shape. Therefore, brazing failure hardly occurs when the tube 210 is inserted into the header tanks 130 and 135 and brazed.

Further, the width of the insertion hole for the tube 210, which is provided in each of the header tanks 130 and 135, is provided in conformity with the width of the region of the tube 210 further on each end portion side with respect to the position of the stepped portion 217 or 218, and hence, when the tube 210 is inserted to reach a predetermined position (position of the stepped portion 217 or 218), the stepped portion abuts against the insertion hole, and the tube 210 cannot be inserted any more. With this, the drainage portion 219 and the insertion port are prevented from overlapping with each other, and hence the brazing failure hardly occurs.

A method of manufacturing the tube 210 is similar to that for the tube 210 in the first embodiment, and the tube 210 is manufactured by press forming an unprocessed tube 240 illustrated in FIG. 6. Note that, the unprocessed tube 240 has an outer shape formed of linear portions formed by flat surfaces 245 and 245, and semi-circular arc portions 242 and 242 formed at both ends of the linear portions. Further, the curvature radius of the semi-circular arc portion 242 is formed to be smaller than a half of a thickness of the unprocessed tube, and a continuous cutout portion 249 is formed across the entire longitudinal region at a boundary between the semi-circular arc portion 242 and the flat surface 245. Note that, a distance from one semi-circular arc portion 242 to the other semi-circular arc portion 242 is the widthwise length of the tube 210 in the region between the stepped portion 217 and the stepped portion 218.

(Usage Example)

As an example in which the heat exchangers (100 and 200) exemplified in the above-mentioned first and second embodiments are used, FIG. 7 illustrates an overall configuration view of an air conditioning apparatus 1 provided in an electric vehicle, for example. This air conditioning apparatus 1 utilizes a so-called heat pump cycle, and switches cooling and heating by switching, with a four-way valve 13, the flow of the refrigerant from a compressor 11 with respect to an out-vehicle heat exchanger 100A and an in-vehicle heat exchanger 100B. Note that, the heat exchanger 100A and the heat exchanger 100B each correspond to any one of the heat exchangers 100 and 200, and in this case, description is made of a case where the heat exchanger 100A and the heat exchanger 100B each correspond to the heat exchanger 100 of the first embodiment.

In the illustrated example, the four-way valve 13 is connected to an ejection port 11 a of the compressor 11. With this, the compressor 11, the in-vehicle heat exchanger 100B, and the out-vehicle heat exchanger 100A are connected as follows. That is, in a case where the four-way valve 13 is connected in a state as indicated by broken lines (heating operation), the refrigerant ejected from the compressor 11 flows into the in-vehicle heat exchanger 100B, and the refrigerant that has passed through the in-vehicle heat exchanger 100B flows into the out-vehicle heat exchanger 100A via an expansion valve 15 so that the refrigerant returns to an intake port 11 b of the compressor 11 via the four-way valve 13. Further, in a case where the four-way valve 13 is connected in a state as indicated by solid lines (cooling operation), the refrigerant ejected from the compressor 11 flows into the out-vehicle heat exchanger 100A, and the refrigerant that has passed through the out-vehicle heat exchanger 100A flows into the in-vehicle heat exchanger 100B via the expansion valve 15 so that the refrigerant returns to the intake port 11 b of the compressor 11 via the four-way valve 13. Note that, a cooling fan 17 is provided adjacent to the out-vehicle heat exchanger 100A.

In an in-vehicle unit of the air conditioning apparatus 1, a damper 21 for intake air switching and a blower 23 are provided on an upstream side of a ventilating duct 20 provided with the heat exchanger 100B. Further, on a downstream side of the ventilating duct 20, a heater unit 25 for heating assistance is provided, and an amount of air passing through the heater unit 25 is adjusted by a damper 27 for discharge air switching. Outlet ports 29 a, 29 b, and 29 c of the ventilating duct 20 are for DEF, FACE, and FOOT, respectively, and dampers 30 a, 30 b, and 30 c respectively provided thereto can adjust the amount of air to be discharged from the outlet ports 29 a, 29 b, and 29 c.

In such an air conditioning apparatus 1, even when condensed water generated through dew condensation adheres to the in-vehicle heat exchanger 100B in the case of cooling operation, the condensed water is drained through the drainage portion 119 provided in the tube 110 of the heat exchanger 100B. Further, even when condensed water adheres to the out-vehicle heat exchanger 100A in the case of heating operation, the condensed water is drained through the drainage portion 119 provided in the tube 110 of the heat exchanger 100A.

The embodiments of the present invention have been described above in detail with reference to the drawings, but specific configurations are not limited to those embodiments, and the present invention also encompasses design changes and the like without departing from the gist of the present invention. Further, mutual use of technologies among the above-mentioned embodiments is possible as long as the objects, the configurations, and the like do not have particular contradictions and problems. For example, description is made of an example in which both the widthwise ends of the tube have a semi-circular arc shape, but the present invention is not limited thereto. Both the widthwise ends of the tube may have a shape that is not curved, such as a rectangular shape.

Further, description is made of an example in which the drainage portion is provided in each widthwise end portion of the tube, but the present invention is not limited thereto, and the drainage portion may be formed only on one widthwise end side of the tube. In this case, it is known that a larger amount of condensed water adheres to the end portion of the tube on the windward side, and hence it is preferred that the heat exchanger be configured so that air is blown by a fan from the side on which the drainage portion is provided.

REFERENCE SIGNS LIST

-   -   100 heat exchanger     -   110 tube (tube for heat exchanger)     -   110 a end portion     -   110 b end portion     -   117 stepped portion     -   118 stepped portion     -   119 drainage portion     -   120 fin 

1. A tube for a heat exchanger, the tube through which a refrigerant flows being formed into a flat plate shape, the tube comprising stepped portions at both end portions in a refrigerant flowing direction, respectively, wherein the tube has a widthwise length in a region on an end portion side with respect to a position of each of the stepped portions, the widthwise length being defined in a longitudinal direction of a cross-section orthogonal to the refrigerant flowing direction, the widthwise length being smaller than a widthwise length in a region between both the stepped portions, and wherein the tube further comprises a drainage portion at a predetermined position between both the stepped portions along the refrigerant flowing direction.
 2. A tube for a heat exchanger according to claim 1, wherein the widthwise length in the longitudinal direction of the cross-section orthogonal to the refrigerant flowing direction of the region on the end portion side with respect to the position of the each of the stepped portions is formed to become smaller toward the end portion.
 3. A heat exchanger, comprising the tube for a heat exchanger according to claim
 1. 4. A method of manufacturing a tube for a heat exchanger, the method comprising press-forming a tube for a heat exchanger, which has a drainage portion formed therein at at least one widthwise side end portion in a longitudinal direction of a cross-section orthogonal to the refrigerant flowing direction along a refrigerant flowing direction, to thereby flatten parts of the drainage portion at both end portions in the refrigerant flowing direction so that a width in the longitudinal direction of the cross-section orthogonal to the refrigerant flowing direction of each part obtained by the flattening is smaller than a width in the longitudinal direction of a cross-section orthogonal to the refrigerant flowing direction between both side end portions.
 5. A heat exchanger, comprising the tube for a heat exchanger according to claim
 2. 